Solid formulation

ABSTRACT

A solid formulation of an agrochemical is prepared by forming a melt containing at least one agrochemical and at least one thermoplastic binder having a melting point or glass temperature of greater than 35° C., briquetting the melt by dividing it into drops in a first step and solidifying these drops by cooling in a second step, characterized in that the melt additionally comprises a liquid non-volatile solvent for the agrochemical.

This application is a 371 of International Application No.PCT/GB02/01146 filed Mar. 13, 2002, which claims priority to GB0106469.0, filed Mar. 15, 2001, the contents of which are incorporatedherein by reference.

This invention relates to a solid formulation and in particular to asolid agrochemical formulation.

In WO 99/21419 there is disclosed a solid formulation of an agrochemicalobtainable by preparing a melt comprising from 1 to 80% by weight of anactive compound usable in crop protection or a combination of suchactive compounds; 20 to 99% by weight of at least one thermoplasticbinder having a melting point or glass temperature of more than 70° C.;and 0 to 20% by weight of additives, the sum of all the ingredientsbeing 100% by weight and subsequent briquetting by dividing thethermoplastic melt into drops in a first step and solidifying the dropsby cooling in a second step. Briquetting of melts of high viscosity withthe aid of a Rotoformer (Rotoformer is a trademark of Sandvik ProcessSystems GMbH, Stuttgart) is known and is described for example in U.S.Pat. No. 4,279,579. Briquettes are solid shaped articles (“buttons”)which are formed when a material of high viscosity, while passingthrough one or more openings or by means of any other division process,is divided into small drop-like amounts which are subsequently cooled tosolid shaped articles, for example on a moving transport surface.Buttons formed for example by a Rotoformer are a very useful solidpresentation for an agrochemical. The diameter is readily controlled inthe range for example of 1 to 35 mm and the buttons so formed are easyto disperse when a suitable thermoplastic binder is used. The buttonsare of a consistent size giving more accurate dosing and efficientpacking. The buttons are generally heat stable and dust-free and can beformed in a high throughput process.

WO 99/121419 does not include polyethylene glycol in its list ofsuitable thermoplastic binders, and on page 2, lines 31 to 42 thedescription refers to WO 93/25074 which is stated to describeformulation by means of a Rotoformer using polyethylene glycol as binderfor compounds such as diuron. WO 99/21419 states that such melts areunsatisfactory and did not result in any “solid solution” onsolidification.

Solid presentations of low-melting solid agrochemicals frequently sufferfrom a problem of crystallisation of the agrochemical ingredient. Thuswhilst it may be possible to produce an apparently satisfactory solidformulation, it is often the case that crystallisation is initiated overthe time-scale that solid formulations are typically stored incommercial practice. Once small crystals are nucleated, they may growrapidly and tend to migrate to the surface of the solid presentation.The consequence is greatly increased operator exposure to theagrochemical and potential release of essentially undiluted solidagrochemical to the environment. The formation of large crystals ofagrochemical may also reduce the ability of the solid formulation todissolve or disperse readily in water to form an acceptable spraysolution.

We have found that crystallisation of a water-insoluble, low-meltingsolid agrochemical may take place within as little as 10 days when asolid presentation is formed using the process such as that described inWO 93/255074 and WO 99/21419.

According to the present invention there is provided a process forpreparing a solid formulation of an agrochemical which comprises forminga melt containing at least one agrochemical and at least onethermoplastic binder having a melting point or glass temperature ofgreater than 35° C., briquetting the melt by dividing it into drops in afirst step and solidifying these drops by cooling in a second step,characterised in that the melt additionally comprises a liquidnon-volatile solvent for the agrochemical.

The way in which the melt is prepared is not crucial and the solidagrochemical and the solid binder may be mixed together and then meltedor separate pre-melts may be mixed or one solid may be added to the meltof the other. In some circumstances it may be preferred to add solidagrochemical to the melt of the binder since the agrochemical may bepartially soluble in the binder melt or the binder melt may otherwisedepress the melting point of the agrochemical.

We have found that not only does the process of the present inventionprovide a solid presentation in which no crystallisation of agrochemicalis observed over an extended period, but also the solid presentation,for example the buttons, remain non-sticky and without significantagglomeration in storage. This is particularly surprising in view of thefact that high levels of liquid solvent are retained in the button andthat the thermoplastic binder may have a melting point or glasstransition temperature below that described in WO 99/21419. Furthermoredespite the presence of liquid solvent component and the potential useof a thermoplastic binder of lower melting point or glass transitiontemperature, we have not encountered any problem with solidification ofthe melt and the process of the present invention provides substantiallynon-tacky buttons. It is a particular economic advantage of the processof the invention that melt solidification is involved and that heat doesnot have to be supplied for the evaporation of a solvent such as water.

Whilst it is preferred on economic and environmental grounds that only aminor proportion of the liquid non-volatile solvent for the agrochemicalis lost by evaporation during the processing of the melt, a solvent is“non-volatile” as that term is used herein provided that at least aproportion of the solvent remains in final product. The solvent shouldbe liquid under ambient conditions and whilst the scope of the presentinvention is not to be taken to be limited by any one particular theory,it is believed that the agrochemical remains in solution in the solventwithin the confines of the solid presentation, although there may inaddition be complex interaction with the solid thermoplastic binder. Itis probable that this is the determining factor in preventingcrystallisation.

The term “agrochemical” as used herein includes any crop protection orpublic health active ingredient or any adjuvant used to enhance thebioperformance of a crop protection or public health active ingredient.The term includes a mixture of active ingredients, a mixture ofadjuvants or a mixture of one or more active ingredients and one or moreadjuvants. Typical agrochemicals include herbicides, plant growthregulants, insecticides (which term includes agents for the control ofmites or nematodes), and fungicides. As noted above, the presentinvention solves or mitigates problems of crystal formation and growthwhich are particularly prevalent with low-melting agrochemicals and inparticular low-melting agrochemicals having a low water solubility. Thusin one embodiment the process of the present invention is particularlysuitable for agrochemicals having a a melting point below 120° C. and inparticular below 80° C. and in particular for such agrochemicals whichhave a low water solubility, for example a solubility in water at 25° C.of less than 10 mg/ml, for example less than 1 mg/ml and in particularless than 0.1 mg/ml. Examples of such agrochemicals include insecticidessuch as tefluthrin (melting point 43° C.), lambda cyhalothrin (meltingpoint 49° C.) and its constituent isomers, pirimicarb (melting point 92°C.), strobilurin fungicides such as azoxystrobin (melting point 116°C.), picoxystrobin (melting point 74° C.) and tralkoxydim (melting point106° C.). The process of the present invention is particularlyapplicable to the formation of solid presentations of lambdacyhalothrin, an active ingredient which is especially prone tocrystallisation problems in solid presentations. References herein tolambda cyhalothrin include its constituent isomers and in particular(S)-α-cyano-3-phenoxybenzyl(Z)-(1R,3R)-3-(2-chloro-3,3,3-trifluoropropenyl)-2,2-dimethylcyclopropanecarboxylate(gamma cyhalothrin).

The advantages of process of the present invention are not howeverrestricted to the use of low-melting agrochemicals. Agrochemicals havinga melting point above 120° C. may nevertheless be soluble in a melt ofthe thermoplastic binder and solvent at a much lower temperature. Wehave found for example that thiamethoxam, despite having a melting pointof 139° C. is readily soluble in a melt comprising polyethylene gycoland methyl oleate as solvent maintained at about 65 to 70° C. and formsa clear liquid melt at this temperature. Indeed, it is not essential foragrochemical to be soluble in the melt and the agrochemical may bepresent in part or wholly in the form of a solid dispersion. For allsuch presentations we have found that the presence of the solvent incombination with the thermoplastic binder provides advantageousbutton-forming properties. When a thermoplastic binder with low glasstransition temperature such as polyethylene glycol is used, non-stickybuttons may be formed at an advantageously low processing temperature.

Further examples of agrochemicals which may be used in the process ofthe present invention will occur to those skilled in the art and includefor example Acequinocyl, Acaricide, m.p. 59.6; Aclonifen, Herbicide,m.p. 81–82; Acrinathrin, Acaricide, Isecticide, m.p. 82.5; AKH-7088,Herbicide, m.p. 57.7–58.1; Alachlor, Herbicide, m.p. 40.5–41.5;Alanycarb, Insecticide, m.p. 46.8–47.2; Ametryn, Herbicide, m.p.86.3–87.0; Amitraz, Acaricide, Insecticide, m.p. 86–88; Ancymidol, Plantgrowth regulator, m.p. 110–111; Anilofos, Herbicide, m.p. 50.5–52.5;Azaconazale, Fungicide, m.p. 112.6; Azinphos-ethyl, Insecticide,Arcaricide, m.p. 50; Azinophos-methyl, Insecticide, m.p. 73;Azoxystrobin, Fungicide, m.p. 116; Beflubutamid, Herbicide, m.p. 75;Benalaxyl, Fungicide, m.p. 78–80; Bendiocarb, Insecticide, m.p.124.6–128.7 Benfluralin, Herbicide, m.p. 65–66.5; Benfurestate,Herbicide, m.p. 30.1; Benoxacor, Herbicide safener, m.p. 107.6;Bensulide, Herbicide, m.p. 34.4; Bensultap, Inseticide, m.p. 83–84;Benzoximate, Acaricide, m.p. 73; Bifenazate, Acaricide, m.p. 120–124;Bifenox, Herbicide, m.p. 84–86; Bifenthrin, Insecticide, Acaricide, m.p.68–70.6; Bioresmethrin, Insecticide, m.p. 32; Biphenyl, Fungicide, m.p.69–71; Bromopropylate, Acaricide, m.p. 77; Bromuconazole, Fungicide,m.p. 84; Bupirimate, Fungicide, m.p. 50–51; Buprofezin, Insecticide,Acaricide, m.p. 104.5–105.5; Butafenacil, Herbicide, m.p. 113; Butralin,Herbicide, Plant growth regulator, m.p. 61; Butroxydim, Herbicide, m.p.80.8; Cafenstrole, Herbicide, m.p. 114–116; Carbetamid, Herbicide, m.p.119; Carboxin, Fungicide, m.p. 91.5–92.5; CGA 50 439, Acaricide,Ixodicide, m.p. 44; Chlorbromuron, Herbicide, m.p. 95–97; Chlordane,Insecticide, m.p. 104–107; Chlorfenapyr, Insecticide, Acaricide, m.p.100–101; Chlorpropham, Herbicide,Plant growth regulator, m.p. 41.4;Chlorpyrifos, Insecticide, m.p. 42–43.5; Chlorpyrifos-methyl,Insecticide, Acaricide, m.p. 45.5–46.5; Chlozolinate, Fungicide, m.p.112.6; Cinidon-ethyl, Herbicide, m.p. 112.2–112-7; Clodinafop-propargyl,Herbicide, m.p. 59.5; Cloquintocet-mexyl, Herbicide safener, m.p. 69.4;Codlemone, Insect pheromone, m.p. 32; Coumaphos, Insecticide, m.p. 95;Cycloxydim, Herbicide, m.p. 41; Cyfluthrin, Insecticide, m.p. 64–101;Beta-Cyfluthrin, Insecticide, m.p. 81–106; Cyhalofop-butyl, Herbicide,m.p. 50; Cypermethrin, Insecticide, m.p. 61–83; Alpha-Cypermethrin,Insecticide, m.p. 78–81; Beta-Cypermethrin, Insecticide, m.p. 64–71;Theta-Cypermethrin, Insecticide, m.p. 81–87; Cyproconazole, Fungicide,m.p. 106–109; Cyprodinil, Fungicide, m.p. 75.9; 2,4-DB, Herbicide, m.p.117–119; DDT, Insecticide, m.p. 108.5–109; Deltamethrin, Insecticide,m.p. 100–102; Desmedipham, Herbicide, m.p. 120; Dichlofluanid,Fungicide, m.p. 106; Dichlorprop, Herbicide, m.p. 116–117.5;Dichlorprop-P, Herbicide, m.p. 121–123; Diclofop-methyl, Herbicide, m.p.39–41; Dicofol, Acaricide, m.p. 78.5–79.5; Diethofencarb, Fungicide,m.p. 100.3; Difenoconazole, Fungicide, m.p. 78.6; Diflumetorim,Fungicide, m.p. 46.8–48.7; Dimepiperate, Herbicide, m.p. 38.8–39.3;Dimethametryn, Herbicide, m.p. 65; Dimethyvinphos, Insecticide, m.p.69–70; Dinitramine, Herbicide, m.p. 98–99; Dinobuton, Acaricide,Fungicide, m.p. 61–62; Diphenylamine, Fungicide, m.p. 53–54; Dithiopyr,Herbicide, m.p. 65; Dodemorph, Fungicide, m.p. 71; Edifenphos,Fungicide, m.p. −25; EPN, Insecticide, Acaricide, m.p. 34.5;Ergocalciferol, Rodenticide, m.p. 115–118; Esfenvalerate, Insecticide,m.p. 59.0–60.2; Ethalflurallin, Herbicide, m.p. 55–56; Ethofumesate,Herbicide, m.p. 70–72; Ethychlozate, Plant growth regulator, m.p.76.6–78.1; Etobenzanid, Herbicide, m.p. 92–93; Etofenprox, Insecticide,m.p. 36.4–38.0; Etoxazole, Acaride, m.p. 101–102; Etridiazole,Fungicide, m.p. 19.9; Famphur, Insecticide, m.p. 522.–53.5; Fenamiphos,Nematicide, m.p. 49.2; Fenarimol, Fungicide, m.p. 117–119; Fenazaquin,Acaricide, m.p. 77.5–80; Fenbuconazole, Fungicide, m.p. 124–126;Fenchlorazole-ethyl, Herbicide safener, m.p. 108–112; Fenclorim,Herbicide safener, m.p. 96.9; Fenfuram, Fungicide, m.p. 109–110;Fenobucarb, Insecticide, m.p. 31–32; Fenothiocarb, Acaricide, m.p.40–41; Fenoxaprop-P-ethyl, Herbicide, m.p. 89–91; Fenoxycarb,Insecticide, m.p. 53–54; Fenpropathrin, Acaricide, Insecticide, m.p.45–50; Fenpyroximate, Acaricide, m.p. 101.1–102.4; Fentin, Fungicide,Algicide, molluscicide, m.p. 118–120; Fenrtazamide, Herbicide, m.p. 79;Fenvalerate, Insecticide, Acaricide, Ixodicide, m.p. 39.5–53.7;Flamprop-M, Herbicide, m.p. 72.5–86; Fluazinam, Fungicide, m.p. 115–117;Fluazolate, Herbicide, m.p. 79.5–80.5; Fluchloralin, Herbicide, m.p.42–43; Flufenacet, Herbicide, m.p. 75–77; Flumetralin, Plant growthregulator, m.p. 101.0–103.0; Flumiclorac-pentyl, Herbicide, m.p.88.9–90.1; Fluoroglycofen-ethylen, Herbicide, m.p. 65; Flurazole,Herbicide safener, m.p. 51–53; Flurenol, Herbicide, m.p. 71;Flurochlordone, Herbicide, m.p. 40.9; Fluroxypyr (-mepthyl), Herbicide,m.p. 58.2–60; Flurprimidol, Plant growth regulator, m.p. 93.5–97;Flusilazole, Fungicide, m.p. 53–55; Fluthiacet-methyl, Herbicide, m.p.105.0–106.5; Flutolanil, Fungicide, m.p. 104–105; Furalaxyl, Fungicide,m.p. 70–84; Furilzole, Herbicide safener, m.p. 96.6–97.6; Haloxyfop,Herbicide, m.p. 107–108; Gamma HCH, Insecticide, m.p. 112.86;Heptachlor, Insecticide, m.p. 95–96; Hexaconazole, Fungicide, m.p.110–112; Hexythiazox, Acaracide, m.p. 108.0–108.5; Hydroprene,Insecticide, m.p. Liquid; Imazalil, Fungicide, m.p. 52.7;Imazamethabenz-methyl, Herbicide, m.p. 113–153; Imibencolazole,Fungicide, m.p. 89.5–90; Indanofan, Herbicide, m.p. 60.0–61.1;4-indol-3-ylbutyric acid, Plant growth regulator, m.p. 123–125;Indoxacarb, Insecticide, m.p. 88.1; Ipconazole, Fungicide, m.p. 88–90;Isoprocarb, Insecticide, m.p. 93–96; Isopropy O-(methoxyaminothiophosphoryl) salicylate, Insecticide, m.p. 45–46; Isoprothiolane,Fungicide, Plant growth regulator, m.p. 54–54.5; Isouron, Herbicide,m.p. 119–120; Kinoprene, Insect growth regulator, m.p. 115–116;Lactofen, Herbicide, m.p. 44–46; Linuron, Herbicide, m.p. 93–95; MCPA,Herbicide, m.p. 119–120.5; MCPA-thioethyl, Herbicide, m.p. 41–42;Mefenpyr-diethyl, Herbicide safener, m.p. 50–52; Mepronil, Fungicide,m.p. 92–93; Metazachlor, Herbicide, m.p. 85; Metconazole, Fungicide,m.p. 110–113; Methabenz thiazuron, Herbicide, m.p. 119–121;Methidathion, Insecticide, Acaricide, m.p. 39–40; Methiocarb,Mollucicide, Insecticide, Acaricide, Bird repellent, m.p. 119;Methoxychlor, Insecticide, m.p. 89; Methyldymron, Herbicide, m.p. 72;Metobenzuron, Herbicide, m.p. 101–102.5; Metobromuron, Herbicide, m.p.95.5–96; Metominostrobin, Fungicide, m.p. 87–89; Monolinuron, Herbicide,m.p. 80–83; Myclobutanil, Fungicide, m.p. 63–68; Napropamide, Herbicide,m.p. 74.8–75.5; Neburon, Herbicide, m.p. 102–103; Nitrapyrin,Bactericide, nitrification inhibitor, m.p. 62.5–62.9;Nitrothal-isopropyl, Fungicide, m.p. 65; Nonanoic acid, Herbicide, Plantgrowth regulator, m.p. 12; Oxabetrnil, Herbicide safener, m.p. 77.7;Oxadiazon, Herbicide, m.p. 87; Oxpoconazole fumerate, Fungicide, m.p.123.6–124.5; Oxyfluorphen, Herbicide, m.p. 85–90; Parathion-methyl,Insecticide, m.p. 35–36; Pendimethalin, Heribcide, m.p. 54–58;Pentanochlor, Herbicide, m.p. 85–86; Pentoxazone, Herbicide, m.p. 104;Permethrin, Insecticide, m.p. 34–35; 2-Phenylphenol, Fungicide, m.p. 57;Phosalone, Insecticide, Acaricide, m.p. 42–48; Phosmet, Insecticide,Acaricide, m.p. 72.0–72.7; Picolinafen, Herbicide, m.p. 107.2–107.6;Pindone, Rodenticide, m.p. 108.5–110.5; Polynactins, Acaricide, m.p.111–112; Prochloraz, Fungicide, m.p. 46.5–49.3; Prodiamine, Herbicide,m.p. 122.5–124; Prometon, Herbicide, m.p. 91–92; Prometryn, Herbicide,m.p. 118–120; Propachlor, Herbicide, m.p. 77; Propanil, Herbicide, m.p.91.5; Propaquizafop, Herbicide, m.p. 66.3; Propham, Herbicide, Plantgrowth regulator, m.p. 87.0–87.6; Pyrazolynate, Herbicide, m.p.117.5–118.5; Pyrazophos, Fungicide, m.p. 51–52; Pyrazoxyfen, Herbicide,m.p. 111–112; Pyributicarb, Herbicide, Fungicide, m.p. 85.7–86.2;Pyridaben, Insecticide, Acaricide, m.p. 111–112; Pyriaphenthion,Insecticide, Acaricide, m.p. 54.5–56.0; Pyrifenox, Fungicide, m.p.Liquid; Pyrimethanil, Fungicide, m.p. 96.3; Pyrinidifen, Acaricide,Insecticide, m.p. 69.4–70.9; Pyriminobac-methyl, Herbicide, m.p. 105;Quinoxyfen, Fungicide, m.p. 106–107.5; Quizalofop, Herbicide, m.p.91.7–92.1; Quizalofop-P, Herbicide, m.p. 76.1–77.1; Resmethrin,Insecticide, m.p. 56.5; Silthiofam, Fungicide, m.p. 86.1–88.3; Simetryn,Herbicide, m.p. 82–83; Pinosat, Insecticide, m.p. 84–99.5;Sulfentrazone, Herbicide, m.p. 121–123; Sulfur, Fungicide, Acaricide,m.p. 114.5; Tebuconazole, Fungicide, m.p. 105; Tebufenpyrad, Acaricide,m.p. 61–62; Tecnazene, Fungicide, Plant growth regulator, m.p. 99;Temephos, Insecticide, m.p. 30.0–30.5; Tepraloxydim, Herbicide, m.p. 74;Terbumeton, Herbicide, m.p. 123–124; Terbutryn, Herbicide, m.p. 104–105;Tetrachlorvinphos, Insecticide, Acaricide, m.p. 94–97; Tetramethrin,Insecticide, m.p. 68–70; Thenylchlor, Herbicide, m.p. 72–74; Thiazopyr,Herbicide, m.p. 77.3–79.1; Tolclofos-methyl, Fungicide, m.p. 78–80;Tolylfluanid, Fungicide, m.p. 93; Tralkoxydim, Herbicide, m.p. 106;Triadimefon, Fungicide, m.p. 78–82; Tri-allate, Herbicide, m.p. 29–30;Triazamate, Insecticide, m.p. 54; Trietazine, Herbicide, m.p. 102–103;Trifloxystrobin, Fungicide, m.p. 72.9; Trifluralin, Herbicide, m.p.48.5–49; Trimethacarb, Insecticide, Molluscicide, m.p. 105–114;Vinclozolin, Fungicide, m.p. 108; Vitamin B 3, Rodenticide, m.p. 84–85;XMC, Insecticide, m.p. 99; Xylylcarb, Insecticide, m.p. 79–80.

One skilled in the art will be able to select a suitable solvent for theagrochemical. It is desirable that the solvent is stable at the melttemperature used and is compatible with the thermoplastic binder suchthat a homogeneous melt is formed Preferably the solvent dissolvessufficient of the agrochemical to provide the desired loading ofagrochemical in the final solid presentation. The selection of thesolvent will be illustrated by way of example with particular referenceto the agrochemical lambda cyhalothrin, although the solvents listedhave broad applicability to a wide range of agrochemicals suitable foruse in the process of the present invention

Commercially effective solid presentations of lambda cyhalothringenerally contain from about 2.5% active ingredient by weight to about5% by weight of active ingredient. There is a commercial need for solidpresentations containing higher loadings, for example about 10% byweight, but this has hitherto been difficult to achieve. Using theprocess of the present invention it is possible to obtain a loading ofat least 10% and in many instances 20% or higher of lambda cyhalothrinin the final solid product. Use of excessive levels of solvent in theprocess of the present invention, for example greater than about 40% to50% w/w in the melt, is likely to lead to a sticky product and thistherefore places an upper limit on the amount of solvent that can beused and, depending on the solubility of the agrochemical in thesolvent, will determine the maximum concentration of the agrochemical inthe melt and in the resultant button. Thus for example if a 10% loadingof lambda cyhalothrin is required in the solid product and the solventcontent of the melt or final product is 20% w/w, then 10 parts of lambdacyhalothrin must be soluble in 20 parts of solvent, giving a desiredsolubility of 10 in 30 or 33%. It is not of essential to operate at thelimit of the solubility of the agrochemical in the solvent and ifdesired concentrations of agrochemical above the solubility limit may beused. Surprisingly, the buttons resulting from such melts do not exhibitcrystallisation of the active ingredient. In some instances, even thoughthe solubility limit of the agrochemical in the solvent may be exceeded,a homogeneous melt may still be obtained as a result of the combinedsolvent power of the solvent and the molten thermoplastic binder. Asnoted above, it is also possible for excess agrochemical to be presentin the melt as a dispersed solid.

It is an additional feature of the use of lambda cyhalothrin thatundesirable epimerisation of the isomers may take place at high pH andsolvents are preferably of pH below about 7. If desired the system maybe acidified to a pH of for example below about pH 6 by the addition ofa suitable acidifying agent such as citric acid. We have found thatcitric acid melts or is otherwise soluble in the melt to form ahomogeneous melt system.

The solvent should be liquid at ambient temperature and where polymericsolvents are specified, the molecular weight should be such that thesolvent is liquid at ambient temperature. Mixtures of solvents may beused. Suitable solvents for use in the process of the present inventioninclude phosphate esters, propylene carbonates, phthalates, methylesters of fatty acids, polypropylene glycols, polystyrene glycol fattyacid esters, ethoxylated fatty acid methyl esters, N-alkyl pyrrolidonesand liquid paraffin. Such solvents are particularly suitable for examplewhen using lambda cyhalothrin as the agrochemical. Examples of suitablephosphate esters include cresyl diphenyl phosphate, tri-n-butylphosphate, 2-ethylhexyl diphenyl phosphate and tributoxyethyl phosphate.The solubility (% w/w) of lambda cyhalothrin in such solvents isgenerally of the order of 20% to 40% at 10° C.

Examples of suitable propylene carbonates include4-methyl-dioxolanone-2-one. Examples of suitable phthalates includebenzyl butyl phthalate. Examples of suitable methyl esters of fattyacids include methyl oleate, methyl laurate and methyl soyate. Examplesof suitable polyethylene glycol fatty acid esters include PEG-300monopelargonate, PEG 200 mono-oleate, PEG-300 mono-oleate and PEG-400mono-oleate. Examples of N-alkylpyrolidones include N-methylpyrrolidone,N-octylpyrrolidone and N-dodecylpyrrolidone.

Solvents may be water-miscible, water-immiscible or dispersable inwater. Whilst we have obtained very satisfactory results usingwater-miscible solvents such as N-alkylpyrrolidones, it is believed thatwater-immiscible solvents, in particular those which disperse readily inwater, may generate agrochemical-containing emulsions when the button isdispersed in water ready for spraying. Particularly suitable solvents inthis regard are polyethylene glycol fatty acid esters which are readilydispersed in water and form self-emulsifying systems. We have found thatbuttons formed using a polyethylene glycol fatty acid ester as solventform very fine emulsion droplets (less than one micron average diameter)with a narrow size distribution when the button is dissolved in water.The button is in consequence readily dispersed in water and the emulsionformed is of excellent stability whilst the agrochemical is effectivelyand evenly dispersed as a solution in the solvent droplets. Suitablepolyethylene glycol fatty acid esters have a fatty acid alkyl chainlength of from 6 to 25, for example from 8 to 20 and a polyethyleneglycol molecular weight of from 100 to 500, for example from 200 to 400.

In WO 99/21419 it is stated that suitable thermoplastic binders arepolymeric binders or binders of low molecular weight which can beprocessed thermoplastically without decomposition and which, incombination with the active compound and other additives do not givesolid forms which are prone to cold flow. Such thermoplastic binders arestated to have a melting point or glass temperature of more than 70° C.and preferably from 80° C. to about 200° C. Such binders are alsoeffective in the process of the present invention and accordinglyexamples of suitable binders are polyvinylpyrrolidone (PVP); copolymersof N-vinylpyrrolidone (NVP) and vinyl esters, especially vinyl acetate;copolymers of vinyl acetate and crotonic acid; partially hydrolysedpolyvinyl acetate; polyvinyl alcohol, poly (hydroxyalkyl acrylates) (forexample C₁- or C₂-alkyl); poly(hydroxyalkyl methacrylates) (for exampleC₁- or C₂ alkyl); polyacrylates and polymethacrylates; copolymers ofmethyl methacrylate and acrylic acid; cellulose ethers, especiallymethylcellulose and ethylcellulose; hydroxyalkylcelluloses, especiallyhydroxypropylcellulose; cellulose phthalates, especially celluloseacetate phthalate and hydroxypropyl-methylcellusose phthalate; andmannans, especially galactomannans. Mixtures of thermoplastic bindersmay also be used.

WO 99/21419 does not include polyethylene glycol in its list of suitablethermoplastic binders, and on page 2, lines 31 to 42 the descriptionrefers to WO 93/25074 which is stated to describe formulation by meansof a Rotoformer using polyethylene glycol as binder for compounds suchas diuron. WO 99/21419 states that such melts are unsatisfactory and didnot result in any “solid solution” on solidification. Furthermorepolyethylene glycol, depending on the molelcular weight, may have amelting point or glass temperature of less than the 70° C. specified inWO 99/21419. We have found that, surprisingly in view of the disclosureof WO 99/21419, polyethylene glycol and indeed even polyethylene glycolhaving a melting point or glass temperature below 70° C. is an excellentthermoplastic binder for use in the process of the present invention andexhibits none of the disadvantages suggested by WO 99/21419 or whichmight be expected to result from the low melting point or glasstransition temperature. Indeed, when used with a low-meltingagrochemical such as lambda cyhalothrin, the use of a polyethyleneglycol having a melting point or glass temperature of from about 50° C.to about 80° C. permits the formation of a relatively low-temperaturemelt with consequent cost savings in commercial production. Suchrelatively low melt temperatures are also highly desirable when theagrochemical has a tendency to degrade at higher temperatures. Thuslambda cyhalothrin has a tendency to degrade at temperatures in excessof 100° C. and melt temperatures in the range from about 50° C. to about90° C. are therefore highly suitable. Despite the low melt temperature,we have found that buttons thus formed release readily from thesubstrate onto which they are deposited and remain non-tacky on heatingat 50° C. It will be appreciated however that the thermoplastic bindermust be solid at ambient temperatures and must therefore have a meltingpoint or glass transition temperature of greater than 35° C. It isdesirable that the thermoplastic binder has a melting point or glasstransition temperature of greater than 40° C. and preferably greaterthan 50° C.

Overall therefore the thermoplastic binder for use in the presentinvention may have a melting point or glass transition temperature offrom 40° C. to 200° C. and preferably from 50° C. to 200° C., whilst theparticular benefits of the present invention are most apparent when thethermoplastic binder has a melting point or glass transition temperatureof from 50° C. to 80° C.

Especially suitable thermoplastic binders therefore include polyethyleneglycol having an average molecular weight in the range from about 3400to about 10,000 (corresponding to a melting point or glass temperatureof from 55° C. to 65° C. with a molecular weight of about 8,000 (meltingpoint or glass temperature of 62° C.) being especially preferred.Polyethylene glycol is especially compatible with polyethylene glycolfatty acid esters used as solvent for the agrochemical.

Further thermoplastic binders which may be used in the process of thepresent invention include polyethoxylated fatty acids and alcohols,ethylene oxide/propylene oxide block copolymers polyethoxylatedalkylphenols and long chain fatty acids such as stearic acid (meltingpoint or glass transition temperature 67° C.).

In the process of the present invention the melt is formed intobriquettes or “buttons” by dividing it into drops in a first step andsolidifying these drops by cooling in a second step. The briquettingsuitably takes place by passing the viscous melt through one or moreopenings, but any process for dividing the melt into droplets may beused. Suitable processes for achieving this briquetting process areknown in the art and examples are described for WO 99/21419 andreferences included therein. Suitable equipment is commerciallyavailable. A convenient and commercially available apparatus forcarrying out the briquetting process according to the present inventionis the Rotoformer supplied by Sandvik Process Systems GMbH. Otherprocesses for dividing the melt into drops in the first step will occurto those skilled in the art and include for example spinning disctechniques.

In a typical small-scale process for use in the present invention, anagrochemical such as lambda cyhalothrin (11.2% w/w) is pre-melted ifappropriate and added to a blend comprising EMEREST 2634 (20.0%w/w—PEG-300 monopelargonate) as solvent and TERGITOL XD (1.0% w/w) assurfactant. The blend is well mixed and maintained at a temperaturebetween 65° C. and 70° C. Finally the polyethylene glycol (65.7% w/w,molecular weight 8000) as thermoplastic binder, citric acid (2.0% w/w)if required as an acidifying agent, and if desired a dye (0.1% w/w,waxoline blue) are added to form the melt formulation. Approximately 20liters of the melt material are added to a holding vessel maintained at75° C. The melt is processed to form buttons on a Rotoformermanufactured by Sandvik Process Systems under the following conditions:Belt speed: 19 m/min, Screen pitch: 5 mm, Hole size: 1.2 mm, Inlet temp:59° C. This generates buttons having the following characteristics:Diameter: 3.6 mm, Weight: 9 mg. The melt temperature used will depend onthe nature of the agrochemical and the thermoplastic binder. It will beappreciated that the melting point or glass temperature of thethermoplastic binder may be reduced by the presence of the agrochemical,solvent and other additives if present. Selection of the melttemperature for a given system is however a matter of routineoptimisation. Melt temperatures will typically range from 55° C. to 120°C. and more particularly from about 65° C. to 80° C. when usingpolyethylene-glycol as the thermoplastic binder. As noted above clear,even high-melting agrochemicals may be processed at these temperatureseither in the form of a homogeneous solution in the melt or as aninhomogeneous dispersion.

Conventional additives may be included in the formulation of the presentinvention provided that they are compatible with the other components ofthe melt. In particular it may be desirable to include a surface activeagent or dispersant to assist dissolution or dispersal of the solidbutton in water and to stabilise the aqueous emulsion or dispersion thusformed. Adjuvants may also be added whose primary purpose is to improvethe bioefficacy of the agrochemical. Many suitable wetters, dispersantsand adjuvants are known in the art. Preferred surface active agentsinclude TERGITOL XD (ethylene oxide/propylene oxide block copolymer),LUBROL 17A17 (fatty alcohol ethoxylate), MORWET D425 (sulphonatedalkylnaphthalene formaldehyde condensate, sodium salt), EMPICOL LZ(sodium lauryl sulphate).

Other typical additives include water-soluble or dispersible fillers,colours and stabilizers such as anti-oxidants and light stabilisers.There may be advantages in using additives which are themselves moltenat the melt temperature or are otherwise soluble in the melt, therebyforming a homogeneous melt system. This is not however an essentialfeature of the invention and additives such as dispersible fillers maybe used which are dispersed as a finely divided solid in the melt, andhence in the resultant solid product. Such fillers will usually bedispersible rather than soluble in water once the resultant solidproduct is added to water.

For certain applications a controlled crystallisation of a low-meltingagrochemical may actually be desirable. Thus for example if aninsecticide such as lambda cyhalothrin is to be used for protectantapplication to surfaces such as walls and furnishings, the presence ofsmall crystals of lambda cyhalothrin in combination with a fillerassists the product to adhere to solid surfaces and limits absorptioninto a porous surface. In this way, long-term surface activity over aperiod of months may be maintained. We believe that the use of a fillerpromotes limited but effective crystallisation whilst the overallprocess of the invention prevents excessive crystallisation which wouldlimit the dispersability of the button into water.

If desired dispersability of the button in water may be increased byincluding a gas-generator and an acidic medium. Typical gas-generatorsinclude an alkali metal bicarbonate in the presence an acidic mediumsuch as citric acid. Such systems are stable in the melt but generatecarbon dioxide in the presence of water, thereby aiding thedispersability of the button.

For the majority of applications the buttons will be dissolved in waterin a spray tank and applied using conventional spray equipment Thepresent invention is not so limited however and includescontrolled-release buttons which are applied or broadcast directly tothe soil or for example to a paddy field. In general the thermoplasticbinder used for such applications will have a much lowerwater-solubility, typically associated with a higher molecular weight.In such applications the agrochemical diffuses slowly out of theencapsulating thermoplastic binder under the action of water in theenvironment.

Applications for slow-dispersing buttons include for examplesoil-applied insecticides and the broadcasting of buttons containing anattractant for pest in combination with an agrochemical effectiveagainst that pest.

The present invention may be used to form buttons containing seed and anagrochemical protectant for that seed such as thiamethoxam. For such aprocess the melt temperature should be sufficiently low that theviability of the seed is not compromised. It is for example possible touse polyethylene glycol as the thermoplastic binder for suchapplications. We have found that the presence of the solvent providesfurther and expected advantages in such systems. Thus in the presence ofthe solvent, well-formed and regularly-shaped buttons are producedwhilst in the absence of solvent there is a tendency for the button to“curl up” from the substrate on which it is deposited. The solvent mayalso assist in the release of the button from the plate onto which it isdeposited. We have also found that in the presence of solvent the seedtends to be incorporated at the edge of the button thereby allowingaccess to moisture for germination. We have found that a long-chainfatty acid such as stearic acid is a particularly suitable thermoplasticbinder for use with seeds and shows no significant retardation ofgermination. Liquid paraffin is an example of a suitable solvent for usewith stearic acid. If desired the seed may be coated with a filler toimprove adhesion between the seed and the thermoplastic binder materialforming the button.

The invention is illustrated by the following examples in which allparts and percentages are by weight unless otherwise stated.

EXAMPLE 1

Pre-melted polyethylene glycol (30.4 g, molecular weight 8000—thethermoplastic binder) was added to a blend comprising pre-melted lambdacyhalothrin (5.6 g), N-octyl pyrrolidone (10.0 g—the solvent), TERGITOLXD (0.5 g, ethylene oxide, propylene oxide block copolymer—a non ionicsurfactant ), LUBROL 17A17 (2.5 g, fatty alcohol ethoxylate—adjuvant andcitric acid (1.0 g—acidifying agent). The final blend was well mixed andmaintained at a temperature between 65° C. and 70° C. A dropping pipettewas used to deposit drops of the melt onto a stainless steel plate. Thedrops, typically 5–6 mm in diameter, were allowed to cool to roomtemperature to form buttons, detached from the metal plate and stored ina PET container.

The dispersion time of the buttons in water was measured by a standardtest as follows:

Standard Dispersion Time Test

The dispersion time of the solid was measured by dropping 3 buttons intoa boiling tube (of approximate dimensions 8 inches×1 inch, with awater-tight stopper) filled with tap water at 20° C.±1° C. to leave anullage space of 0.5 to 0.75 inches in the tube. The tube was invertedslowly such that the buttons are not allowed to sit on the bottom of thetube but are allowed to settle through the medium under the influence ofgravity. The time taken for the buttons to completely disperse wasnoted.

As measured by the standard test method given above the dispersion timeof a button sample (of dimension 5–6 mm diameter, 1–2 mm dome height)was approximately 6 minutes.

The mean droplet size (D 4,3) of the resultant oil-in-water emulsion was2.7 microns with 91% of the droplets being less than 5 microns, whenmeasured using a Malvern Mastersizer S.

No caking or tackiness was observed when 10 g of these buttons werestored in a PET container for 17 hours in an oven maintained at 45° C.and then allowed to cool to room temperature.

The buttons were dispersed in water and the resultant emulsion showedexcellent bioefficacy when tested against standard insect species.

The dispersion time of these buttons in water and the mean droplet sizeof the resultant oil-in-water emulsion did not change following storageat room temperature for 5 months. Examination of the aged buttons underthe optical microscope showed no evidence of crystallisation of theactive ingredient. Storage was continued for a further 5 months afterwhich there was still no sign of crystallisation.

COMPARISON 1

The formulation procedure described in Example 1 was repeated with theexception that the solvent (N octyl pyrrolidone) was omitted andreplaced with a higher (equivalent) loading of PEG 8000.

The resultant buttons had very similar initial characteristics to thosedescribed in Example 1. However, after only 10 days of storage at roomtemperature the buttons showed evidence of active ingredientcrystallisation accompanied by a significant decrease in waterdispersibility.

EXAMPLE 2

Pre-melted polyethylene glycol (32.9 g, molecular weight 8000) was addedto a blend comprising pre-melted lambda cyhalothrin (5.6 g), EMEREST2634 (10.0 g, PEG-300 monopelargonate) as solvent, TERGITOL XD (0.5 g anon-ionic surfactant) and citric acid (1.0 g). The final blend was wellmixed and maintained at a temperature between 65° C. and 70° C. Adropping pipette was used to deposit drops of the melt onto a stainlesssteel plate. The drops, typically 5–6 mm in diameter, were allowed tocool to room temperature, detached from the metal plate and stored in aPET container.

The dispersion time in water, as measured by the standard test, for a5–6 mm button sample was approximately 5.5 minutes.

The mean droplet size (D 4,3) of the resultant oil-in-water emulsion was0.86 microns with 100% of the droplets being less than 5 microns, whenmeasured using a Malvern Mastersizer S.

No caking or tackiness was observed when 10 g of these buttons werestored in a PET container for 17 hours in an oven maintained at 45° C.and allowed to cool to room temperature.

The buttons were dispersed in water and the resultant emulsion showedexcellent bioefficacy when tested against standard insect species.

The dispersion time of these buttons in water and the mean droplet sizeof the resultant oil-in-water emulsion did not change following storageat room temperature for 5 months. Examination of the aged buttons underthe optical microscope showed no evidence of crystallisation of theactive ingredient. Examination of the buttons using an Infra Redmicroscope revealed that the active ingredient was fully containedwithin the button and that the external surface of the button was freeof active ingredient.

EXAMPLE 3

Pre-melted polymer SYNPERONIC PE F127 (6.7 g, ethoxylated polypropyleneoxide ethylene oxide/proplylene oxide block copolymer, molecular weight12000) was added to a blend comprising pre-melted lambda cyhalothrin(1.1 g), N-methyl pyrrolidone (2.0 g) and citric acid (0.2 g). The finalblend was well mixed and maintained at a temperature between 65° C. and70° C. A dropping pipette was used to deposit drops of the melt onto astainless steel plate. The drops, typically 5–6 mm in diameter, wereallowed to cool to room temperature, detached from the metal plate andstored in a PET container. The buttons dispersed readily in water. Nocrystallisation was observed after 10 months storage.

EXAMPLE 4

Pre-melted polyethylene glycol (2.0 g, molecular weight 6000) andSYNPERONIC PE F127 (4.0 g), together forming a mixed thermoplasticbinder system, were added to a blend comprising azoxystrobin (2.5 g),N-methyl pyrrolidone (0.5 g) and TERGITOL XD (1.0 g). The final blendwas well mixed and maintained at a temperature between 65° C. and 70° C.A dropping pipette was used to deposit drops of the melt onto astainless steel plate. The drops, typically 5–6 mm in diameter, wereallowed to cool to room temperature, detached from the metal plate andstored in a PET container.

The buttons dispersed relatively slowly in water.

EXAMPLE 5

This Example illustrates the use of a mixture of two agrochemicals.Pre-melted polyethylene glycol (6.3 g, molecular weight 8000) was addedto a blend comprising pre-melted lambda cyhalothrin (0.6 g), EMEREST2634 (1.0 g), TERGITOL XD (0.1 g) and citric acid (0.2 g). The blend waswell mixed and maintained at a temperature between 65° C. and 70° C.Pirimicarb (1.8 g) was mixed in and a clear melt was obtained. Adropping pipette was used to deposit drops of the melt onto a stainlesssteel plate. The drops, typically 5–6 mm in diameter, were allowed tocool to room temperature, detached from the metal plate and stored in aPET container. The buttons dispersed in water with no residue.

EXAMPLE 6

Pre-melted polyethylene glycol (3.4 g, molecular weight 8000) was addedto a blend comprising pre-melted tefluthrin (0.55 g), EMEREST 2634 (1.0g, PEG-300 monopelargonate) and TERGITOL XD (0.05 g, ethylene oxide,propylene oxide block copolymer). The final blend was well mixed andmaintained at a temperature between 65° C. and 70° C. A dropping pipettewas used to deposit drops of the melt onto a stainless steel plate. Thedrops, typically 5–6 mm in diameter, were allowed to cool to roomtemperature to form buttons which were detached from the metal plate andstored in a PET container.

The buttons were water dispersible. The mean droplet size (D 4,3) of theresultant oil-in-water emulsion was 2.75 microns with 87% of thedroplets being less than 5 microns, when measured using a MalvernMastersizer S. The excellent droplet size distribution indicates that nocrystallisation of the tefluthrin had taken place.

EXAMPLE 7

This Example illustrates the use of a reduced amount of solvent suchthat lambda cyhalothrin forms a supersaturated solution (compare Example2). Pre-melted polyethylene glycol (35.4 g, molecular weight 8000) wasadded to a blend comprising pre-melted lambda cyhalothrin (5.6 g),EMEREST 2634 (7.5 g, PEG-300 monopelargonate), TERGITOL XD (0.5 g) andcitric acid (1.0 g). The final blend was well mixed and maintained at atemperature between 65° C. and 70° C. A dropping pipette was used todeposit drops of the melt onto a stainless steel plate. The drops,typically 5–6 mm in diameter, were allowed to cool to room temperatureto form button which were detached from the metal plate and stored in aPET container at RT for 11 months. After storage, the buttons dispersedreadily in water. The mean droplet size (D 4,3) of the resultantoil-in-water emulsion was 0.8 microns with 98% of the droplets beingless than 5 microns, when measured using a Malvern Mastersizer S.Despite the use of a reduced amount of solvent the excellent dropletsize distribution indicates that no crystallisation had taken place.

EXAMPLE 8

This Example illustrates the use of a high loading of agrochemical (20%by weight of lambda cyhalothrin in the final button as compared with 10%by weight in Examples 2 and 7). Pre-melted polyethylene glycol (57.0 g,molecular weight 8000) was added to a blend comprising pre-melted lambdacyhalothrin (20 g), EMEREST 2634 (20.0 g, PEG-300 monopelargonate),TERGITOL XD (1.0 g) and citric acid (2.0 g). The final blend was wellmixed and maintained at a temperature between 65° C. and 70° C. Adropping pipette was used to deposit drops of the melt onto a stainlesssteel plate. The drops, typically 5–6 mm in diameter, were allowed tocool to room temperature to form buttons which were detached from themetal plate and stored in a PET container for 10 months.

Following storage, the buttons dispersed readily in water and the meandroplet size (D 4,3) of the resultant oil-in-water emulsion was 1.2microns with 100% of the droplets being less than 5 microns, whenmeasured using a Malvern Mastersizer S.

EXAMPLE 9

This Example illustrates the use of a filler in the composition.Pre-melted polyethylene glycol (65.8 g, molecular weight 8000) was addedto a blend comprising pre-melted lambda cyhalothrin (11.2 g), N-methylpyrrolidone (5.0 g), TERGITOL XD (1.0 g) and citric acid (2.0 g). Theblend was well mixed and maintained at a temperature between 65° C. and70° C. Silica powder (7.5 g, Degussa FK320) and China clay (7.5 g) werethen stirred into the melt and mixed thoroughly to give a homogeneousdispersion. A dropping pipette was used to deposit drops of the meltonto a stainless steel plate. The drops, typically 5–6 mm in diameter,were allowed to cool to room temperature to form buttons which weredetached from the metal plate and stored in a PET container.

The buttons dispersed readily in water to produce a dispersion that wasused to spray both unglazed ceramic tiles and adult German cockroaches.

EXAMPLE 10

Methyl oleate (20.0 g) was added to pre-melted polyethylene glycol (68.0g, molecular weight 8000). Thiamethoxam (12.0 g) was added to the melt,mixed in and the temperature of the melt maintained between 65° C. and70° C. until a clear liquid was formed. A dropping pipette was used todeposit drops of this melt onto seeds (cabbage, lettuce and tomato),placed in a row, on a stainless steel plate. On cooling to roomtemperature, the resulting button contained the seed asymmetrically,such that the seed was embedded on one side of the hemisphere. Thecoated seed was detached from the metal plate and stored in a PETcontainer.

1. A process for preparing a solid formulation of an agrochemical whichcomprises forming a melt containing at least one agrochemical and atleast one thermoplastic binder having a melting point or glasstemperature of greater than 35° C., briquetting the melt by dividing itinto drops in a first step and solidifying these drops by cooling in asecond step, characterised in that the melt additionally comprises aliquid non-volatile solvent for the agrochemical wherein the solvent isa phosphate ester, a propylene carbonate, a phthalate, a methyl ester ofa fatty acid, a polystyrene glycol fatty acid ester, an ethoxylatedfatty acid methyl ester, polyethylene glycol fatty acid ester, anN-alkyl pyrrolidone or liquid paraffin.
 2. A process according to claim1 wherein the at least one thermoplastic binder is polyvinylpyrrolidone,a copolymer of N-vinylpyrrolidone and a vinyl ester, a copolymer ofvinyl acetate and crotonic acid, partially hydrolysed polyvinyl acetate,polyvinyl alcohol, poly (hydroxyalkyl acrylate), poly(hydroxyalkylmethacrylate), polyacrylate, polymethacrylate, copolymers of methylmethacrylate and acrylic acid, cellulose ether, hydroxyalkylcellulose,cellulose phthalate, a mannan, a polyethylene glycol, a polyethoxylatedfatty acid, and a polyethoxylated fatty alcohol, an ethyleneoxide/propylene oxide block copolymer, a polyethoxylated alkylphenol ora long chain fatty acid.
 3. A process according to claim 1 wherein thesolvent is a polyethylene glycol fatty acid ester having a fatty acidalkyl chain length of from 6 to 25 and a polyethylene glycol molecularweight of from 100 to
 500. 4. A process according to claim 3 wherein theat least one thermoplastic binder is polyethylene glycol.
 5. A processaccording to claim 1 wherein the solid formulation contains seed and theagrochemical is a protectant for that seed.
 6. A process according toclaim 5 wherein the at least one thermoplastic binder is a long-chainfatty acid and the solvent is liquid paraffin.
 7. A process according toclaim 1 wherein the at least one thermoplastic binder has a meltingpoint or glass transition temperature of greater than 50° C.
 8. Aprocess according to claim 1 wherein the at least one thermoplasticbinder has a melting point or glass transition temperature of from 40°C. to 200° C.
 9. A process according to claim 8 wherein the at least onethermoplastic binder has a melting point or glass transition temperatureof from 50° C. to 80° C.
 10. A process according to claim 1 wherein themelt temperature is from 55° C. to 120° C.
 11. A process according toclaim 10 wherein the at least one agrochemical is thiamethoxam.
 12. Aprocess according to claim 11 wherein the at least one agrochemical isthiamethoxam.
 13. A process according to claim 1 wherein the at leastone agrochemical has a melting point below 120° C.
 14. A processaccording to claim 13 wherein the at least one agrochemical has a lowwater-solubility.
 15. A process according to claim 14 wherein the atleast one agrochemical is tefluthrin, lambda cyhalothrin, pirimicarb,axozystrobin, picoxystrobin or tralkoxydim.
 16. A process for preparinga solid formulation of an agrochemical which comprises forming a meltcontaining at least one agrochemical and at least one thermoplasticbinder having a melting point or glass temperature of greater than 35°C., briquetting the melt by dividing it into drops in a first step andsolidifying these drops by cooling in a second step, characterised inthat the melt additionally comprises a liquid non-volatile solvent forthe at least one agrochemical wherein the at least one thermoplasticbinder is polyethylene glycol and the solvent is a phosphate ester, apropylene carbonate, a phthalate, a methyl ester of a fatty acid, apolystyrene glycol, a polystyrene glycol fatty acid ester, anethoxylated fatty acid methyl ester, polyethylene glycol fatty acidester, an N-alkyl pyrrolidone or liquid paraffin.
 17. A processaccording to claim 16 wherein the at least one thermoplastic binder hasa melting point or glass transition temperature of greater than 50° C.18. A process according to claim 2 wherein the at least onethermoplastic binder is polyethylene glycol having an average molecularweight in the range from about 3400 to about 10,000.
 19. A processaccording to claim 16 wherein the at least one thermoplastic binder hasa melting point or glass transition temperature of from 40° C. to 200°C.
 20. A process according to claim 19 wherein the at least onethermoplastic binder has a melting point or glass transition temperatureof from 50° C. to 80° C.
 21. A process according to claim 16 wherein themelt temperature is from 55° C. to 120° C.
 22. A process according toclaim 21 wherein the at least one agrochemical has a melting point above120° C. and is soluble or dispersible in the melt.
 23. A processaccording to claim 16 wherein the at least one agrochemical has amelting point below 120° C.
 24. A process according to claim 23 whereinthe at least one agrochemical has a low water-solubility.
 25. A processaccording to claim 24 wherein the at least one agrochemical istefluthrin, lambda cyhalothrin, pirimicarb, axozystrobin, picoxystrobinor tralkoxydim.
 26. A process according to claim 25 wherein the at leastone agrochemical is thiamethoxam.
 27. A process according to claim 16wherein the at least one thermoplastic binder is a polyethylene glycolhaving an average molecular weight in the range from about 3400 to about10,000.
 28. A process according to claim 16 wherein the solvent is apolyethylene glycol fatty acid ester having a fatty acid alkyl chainlength of from 6 to 25 and a polyethylene glycol molecular weight offrom 100 to
 500. 29. A process according to claim 16 wherein the solidformulation contains seed and at least one agrochemical is a protectantfor that seed.